Log-transformed sample size and lack of multiple correction

Yohannes W.Woldeamanuel, Neurologist-Researcher, Department of Neurology, Stanford University School of Medicine

Published August 15, 2018

van Oosterhout et al. [1] studied group difference of female sex hormones between men with migraine and healthy controls. After reading their article, I have concerns.

First, log-transformed sample size calculation must be followed by log-transformed outcome analysis; [2] this was not the case in this study. [1] Exploring for biological differences in a heterogeneous and common condition like migraine can lead to "significant" findings. I suggest confirming these exploratory results in a larger sample size with migraine clinical phenotyping. A sample size of 15-22 is unusually low for migraine studies.

Second, I expected to see multiple corrections for t tests in figure 1, [1] since comparisons contained either testosterone or estradiol. Bonferonni correction of p level at 0.025 could adjust for multiple testing, in which case the ratio result in figure 1A would not be significant (0.03). [1] This, again, could be due to inadequate sample size estimation.